Conventionally known absolute value calculating means for performing an absolute value calculation of alternating voltage (AC) signals and converting the same into direct-current voltage (DC) signals include full-wave rectification circuits arranged by assembling diodes, or circuits in which such circuits are combined with transformers.
However, it is sufficient to provide a single diode in the case of performing half-wave rectification in such a circuit employing diodes, when remaining half-waves will not be output but ignored. On the other hand, a plurality of elements to be imposed will be required in the case of forming a circuit in which full-wave rectification is performed so that forming the circuit will be troublesome. Moreover, while both of these circuits enable conversion in an effective manner since electric signals are directly converted into electric signals, forward voltage drops due to the diodes will not be zero, so that it may cause errors in the case of performing an absolute value calculation of minute signals using diodes.
The present invention has thus been made in view of these problems, and it is an object thereof to provide an absolute value calculating element for converting alternating-current signals into direct-current signals having a small amount of imposed elements and without causing a specific voltage drop.